87725-96-0Relevant articles and documents
Carbon-carbon bond forming and breaking by a metal-assisted redox process in a nickel(II)-Schiff base complex
Gambarotta, Sandro,Urso, Fabio,Floriani, Carlo,Chiesi-Villa, Angiola,Guastini, Carlo
, p. 3966 - 3972 (2008/10/08)
Alkali metals (M = Li, Na) promote the reductive coupling of imino functional groups in [Ni(salophen)] (salophen = N,N′-ophenylenebis(salicylidenaminato) dianion). By such a reaction, two Ni(salophen) units are joined through a C-C bond to form a dimeric structure, [Ni(salophen)MLn]2 (L = THF; M = Li, n = 2; M = Na, n = 3). No change in the oxidation state of the metal and in its coordination geometry was observed as a consequence of the reaction with alkali metals. In the final dimeric complex salophen acts as a bidentate ligand toward the alkali cation. The most relevant structural parameters concern the C-C bridging unit [1.64 (4) ?, M = Li; 1.58 (2) ?, M = Na] and the change occurring on the C=N imino functional unit of salophen [C-Nav = 1.48 (3) ?; C=Nav = 1.30 (3) ?]. An excess of alkali metals reacted with [Ni(salophen)] promoting its polymerization through a C-C bond formation involving all the C=N units present in the ligand. Mild oxidizing agents (Mel, O2, I2) removed two electrons from the dimeric compounds, promoting the C-C bond cleavage and restoring the original imino group. [Ni(salophen)] was recovered from all these reactions. The attack of the oxidizing agent does not occur at the ligand. Crystallographic details for [Ni(salophen)Li(THF)2]2-2THF: space group C2/c (monoclinic); a = 39.619 (5), b = 12.461 (2), c = 24.522 (4) ?; β = 91.28 (2)°; V = 12 103 ?3; Z = 8; final R factor 0.089 for 1509 observed reflections. Crystallographic details for [Ni(salophen)Na(THF)3]2·C4H 8O2: space group P21/c (monoclinic); a = 11.194 (2), b = 17.597 (3), c = 16.639 (3) ?; β = 90.59 (1)°; V = 3277 ?3; Z = 2; final R factor 0.060 for 1447 observed reflections.
